The present invention relates generally to endoscopic laser coagulators and, more particularly, to an endoscopic laser coagulator adapted to provide laser beam irradiation in an oblique direction relative to the axis of the insertion tube thereof.
Endoscopes are generally adapted to accomplish one or more tasks. For example, endoscopes are often utilized to observe or photograph particular regions within the body as well as to diagnose and obtain samples of tissue cells. In order to perform such operations, conventional endoscopes usually comprise an insertion tube adapted to be introduced to various organs of the body, such as the stomach, respiratory system or intestine, and in which an optical image transmitting fibre is provided to obtain visual observation of the affected area.
Endoscopic laser coagulators are particularly adapted to therapeutically irradiate a diseased region with a laser beam. For example, such laser beam irradiation may be useful for hemostatic purposes or for the elimination of polyps, such as in the stomach or the like, or of constrictions present in the trachea, bronchus, etc.
However, conventional endoscopic laser coagulators have the drawback that in certain applications it is not possible to achieve effective and appropriate laser beam irradiation of the diseased area. More particularly, when the diseased area is located in body organs presenting a limited or restricted space, it is not possible to bend the forward end region of the flexible insertion tube in order to direct the laser beam irradiation in the desired direction. For example, when the flexible insertion tube is introduced into a segmental bronchus in order to therapeutically treat a diseased area on the wall thereof, little or no clearance will exist between the flexible insertion tube and the bronchus wall in order to effect appropriate bending of the insertion tube and, consequently, it has not been possible to use conventional endoscopic laser coagulators to achieve effective and appropriate laser beam irradiation in such applications.
A reduction of the diameter of the flexible insertion tube will not completely resolve the problem discussed above due to certain inherent functional limitations. Thus, when the region to be irradiated is situated on the wall of an organ having a reduced curvature such, for example, as the stomach, the flexible insertion tube of the endoscope inevitably tends to become situated adjacent to the wall of the stomach so that a force which is applied to bend the forward portion of the flexible insertion tube often results in moving the front end region of the flexible insertion tube into contact with the stomach wall thereby rendering the laser beam irradiation of the diseased area impossible.
In an attempt to overcome the problems of therapeutic irradiation by endoscopic laser coagulators as discussed above, and in particular to accomplish laser irradiation of the wall of the bronchus, endoscopic laser coagulators have been utilized in which the desired therapeutic irradiation is effected utilizing the peripheral energy of the laser beam emitted from the laser beam conducting fibre rather than the central portion of the emitted laser beam. Thus, it is understood that in conventional endoscopic laser coagulators, a laser beam is emitted from the forward or leading end of the flexible insertion tube and that such laser beam will normally diverge defining an angle of irradiation of about 10.degree.. As noted above, it has been proposed to utilize the peripheral regions of the diverging irradiation beam to therapeutically treat diseased regions which are situated in areas where it is not possible to bend the flexible tube into direct confronting relationship.
However, this technique has not proven to be entirely satisfactory since its use has often resulted in serious damage to healthy tissue proximate to the diseased region and which is located in the central or normal region of the beam of laser irradiation. Therefore, this technique has proven to be too dangerous to be employed in practice.
Another possible solution to the problems discussed above has been suggested wherein the flexible insertion tube of the endoscope is equipped to provide a lateral irradiation field rather than a view of the field parallel to the axis of the elongate flexible tube. Use of such lateral viewing type flexible insertion tubes, however, will result in the end surface of the laser beam conducting fibre from which the laser beam is emitted to become positioned unduly close to or even in contact with the wall of the organ to be treated. As a consequence, the energy of the laser beam irradiation may become so intense as to actually burn a hole in the organ wall. In addition to the obvious serious implications of such action, the destroyed tissue will tend to cling to the end surface of the laser beam conducting fibre resulting in the destruction thereof with continued use.